Watercraft rear extension



FIG. 1 is a perspective view taken from a rear, left side of a watercraft rear extension according to our design shown on a watercraft shown in dashed lines;

FIG. 2 is a top plan view thereof shown on the watercraft shown in dashed lines;

FIG. 3 is a left side elevation view thereof shown on the watercraft shown in dashed lines;

FIG. 4 is a rear elevation view thereof shown on the watercraft shown in dashed lines;

FIG. 5 is a right side elevation view thereof shown on the watercraft shown in dashed lines; and,

FIG. 6 is a bottom plan view thereof shown on the watercraft shown in dashed lines.

Throughout the Figures, where shown: the dashed lines showing the environment of the watercraft rear extension are for illustrative purposes only and form no part of the claimed design; and the dotted/dashed lines illustrate unclaimed boundaries of surfaces claimed as part of the design. 

CLAIM The ornamental design for a watercraft rear extension, as shown and described. 